Simple Construction of Multistage Stable Silicon-Graphite Nanosheets Composites for Lithium-Ion Batteries

Silicon/carbon composites are considered as the preferred anode materials for high energy density lithium-ion batteries due to their high capacity. However, the high cost of raw materials and the complex preparation process have resulted in expensive cost and poor batch stability of silicon-carbon materials, which have impeded their widespread adoption on a large scale. In this study, a multistage stable silicon-graphite nanosheets composite (Si-NSs/G-NSs@C) with intercalated and core-shell structure was produced from low-cost precursors of silicon nanosheets (Si-NSs) and graphite nanosheets (G-NSs) by simple modification-grafting-coating and heat treatment processes. Benefiting from the effective bonding, citric acid carbon coating, intercalation and core-shell structure, the Si-NSs/G-NSs@C composite exhibits excellent performance for lithium storage. The Si-NSs/G-NSs@C electrode, using the sodium alginate binder system, displays the reversible specific capacity of 821.4 mAh g−1 at 400 mA g−1, with the capacity retention rate of 80% after 200 cycles. When employing lithium polyacrylate as the binder, the composite electrode demonstrates the reversible specific capacities of 1048.9 mAh g−1 at 400 mA g−1 and 723.6 mAh g−1 at 1000 mA g−1. After 200 cycles, the capacity retention rates were 81% and 85%, respectively. In summary, the low-cost precursors, simple and controllable preparation process and excellent electrochemical performance will further promote the market application of silicon/carbon anode materials.